52 DR. D. H. SCOTT ON A NEW TYPE OF MEDULLOSEJE 
order to show the fact more plainly the large-scale fig. 9 (Pl. 8) has been added, from 
which it will be seen that, in spite of some local damage, the continuity of the tissues 
is beyond doubt. This is the first definite case met with of a fusion between two 
independent meristeles, though it will be remembered that there was reason to suspect a 
fusion, on a smaller scale, in connection with meristele œ (see p. 50). 
The meristele with which (8 fuses may be called y, and the product of their fusion B. 
It is of interest to trace the previous history of y as far as possible. 
It is already present in the lowest section as an independent strand lying to the right 
of B; and is practically unaltered in Section LIL, the first figured (fig. 1). From its 
dimensions (5'55 x35 mm.) and form it is improbable that it arose from 6, and more 
likely that it had a common origin with the two meristeles immediately above (fig. 1), 
which, at the base of the series, form a single mass. 
In Section V. (fig. 2) a strand begins to detach itself from y at the top right-hand 
corner; this becomes free in the succeeding sections, and is seen in fig. 4 (from 
Section IX.) at y'; this is a large strand, with a mean diameter of about 2 mm. 
A smaller strand (y") is then detached from the lower end of y (fig. 3, from 
Section VIIL, and figs. 4 & 9, from Section IX.) and the remaining mass fuses, as 
already stated, with the meristele (3. 
In Section X. (which, as will be remembered, is separated by a considerable interval 
from IX.) the fused meristele B is neatly rounded off, and evidently a good deal of 
tissue has been detached from the end corresponding to y. A large strand (B), 
3X25 mm. in diameter, adjacent to this end of B, clearly represents a part of this 
detached mass, and it is probable that the strand exterior to this, and possibly one or 
two smaller neighbouring bundles, shared the same origin. 
In Section XIV. B'has cut off another small bundle, and in XVII. the uppermost 
section of the series, the meristele B appears to be giving off a fresh strand from the 
same end as before (PI. 8. fig. 6) *. 
Only one more point remains to be mentioned in connection with this part of the 
bundle-system. The smaller meristele D, which separated from |3 before its fusion 
with y (see above, p. 51), moves off rapidly to the left, comes into contaet with the stele, 
and gradually becomes embedded in the wood of the latter (figs. 2-6). If this were à 
genuine ease of the re-fusion of a meristele with the stele, it would be of much interest, 
but careful examination has convinced me that the appearance of fusion is delusive, 
and that the meristele has merely been pressed mechanically into the substanee of the 
stele, owing to a crushing-in of the cortical tissues in this region. 
: If we endeavour to sum up the main points in the course of the meristeles as shown 
in the two examples traced, we find that a considerable mass of tissue gradually 
separates from the stele, and successively subdivides into strands of very unequal 
dimensions. The giving-off of small strands may begin before the main meristele has 
become free. Itis not proved that the whole mass is ever completely used up in the 
formation of the smaller strands. The most interesting point is the occurrence of fusion 
The actual separation here is due to Injury, but there are indications of a natural incision having appeared. 
